[LAU] how to install the real time preempt kernel in ubuntu12.04 and make it the defult?

Ralf Mardorf ralf.mardorf at alice-dsl.net
Tue Aug 21 20:53:39 UTC 2012


On Tue, 2012-08-21 at 20:57 +0200, Jeremy Jongepier wrote:
> On 08/21/2012 08:36 PM, david wrote:
> >
> > Debian Sid has an RT kernel available, too.
> 
> Checked the config.
> 
> CONFIG_HZ_250=y
> 
> Or doesn't that matter because
> 
> CONFIG_NO_HZ=y
> 
> ??
> 
> I've never used a tickless kernel, does it perform better or is there no 
> real difference?

Good question. I always set up CONFIG_HZ_1000=y, but I also use HPET.
There's a difference regarding to jitter between Hz 1000 and HPET when
using hardware MIDI. I'm unsure if there's a difference between tickless
yes and no. Some people claim that tickless = yes could cause issues.
Most of my kernels where compiled with tickless = yes and I don't think
that issues I got were related to this. I suspect that tickless did
improve MIDI jitter too, but I don't compare same kernels with tickless
yes/no. Dunno! However, IIRC tickless is only used when we use hrtimer
(HPET)???

Regards,
Ralf



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